Control apparatus



y 1943 J. w. DAws o u Re. 22,314

CONTROL APPARATUS Original Filed Dec. 19, 1930 WITNESS ES f I INVENTOR QMK'M- Y John-W Dawson BYQ 2 g J1 f7 ATTORNEY Reiuued May. 113, 1943 CONTROL APPARATUS John W. Dawson. Wilkinsburg, Pm, assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania riginal No. 1,928,812, dated October a, 1933, Serial No. 503,484, December 19, 1930. Application for reissue January 11, 1934, Serial No.

13 Claims.

My invention relates to control apparatus and has particular relation to control apparatus of a type utilized in producing mechanical reciprocating or rotary motion of a predetermined period.

It is an object of my invention to provide control apparatus capable of delivering an electromechanical force of predetermined periodicity.

Another object of my invention is to provide control apparatus capable of delivering a periodic force of uniform magnitude. 7

A further object of my invention is to provide control apparatus capable of delivering an electro-mechanical force, the magnitude of which .provide, in control apparatus of the type including an inductor, a device whereby the energy arising from a current of predetermined polarity, established in the inductor, is rapidly dissipated in an independent network provided therefor.

A further ancillary object of my invention is to provide in control apparatus of the type including a plurality of electric discharge tubes, that are periodically extinguished, and an inductor, a device whereby said inductor is prevented from influencing the condition of the tubes, by its magnetic action. I 7

According to my invention I provide, acontrol system, for producing a periodic electro-magnetic force, of the type wherein the coil of an electromagnet, is periodically excited by the current traversing a grid controlled electric discharge tube. The potential of the grid of the tube is varied periodically by the action of a commutator disc that coacts with a source of potential independent of the source provided for operating the tube. The periodicity and the amplitude of the force is maintained uniform by reason of the fact that the commutator is rotated in synchronism with the alternations in the power source supplying the potentials for operating the tube.

According to a modification of my invention, the coil of the electro-magnet is excited from a plurality of tubes connected in push-pull relaadjusting the number and tionship. By properly the position of the segments of the commutator associated with the tubes, an electro-magnetic force of any predetermined characteristics may be produced with apparatus of this type.

Finally, the back-electromotive-force, arising from a current established in the coil of the electro-magnet, is prevented from perceptibly distorting the character of the disturbance that is delivered by the system by the action of a rectiiier that is so connected in the system as to shunt the coil. I have found that by the addition of the re tifier, a rather aggravating fault has been remedied.

The novel features that I consider characteris-. tic of my invention are set forth with particularity in the appended claims. The invention itself,

however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments, when read in connection with the accompanying drawing, in which:

Fig. lis a view in perspective illustratin oertain electrical and mechanical features of a comrtriiotfiator utilized in an embodiment of my inven- Fig. 2 is a perspective view of the sector disc of a commutator disc of a specific type.

Fig. 3 is a second perspective view showingcertain additional elements of the commutator disc,

Fig. 4 is a schematic view showing the electrical circuit of an embodiment. of my invention Fig. 5 is a graph illustrating the action of the apparatus shown in Fig. 7,

Fig. 6 is a schematic view showing a modification of my invention,

Fig. '7 is a graph illustrating a characteristic of the. apparatus shown in Fig. 9, and

Figs. 8 and 9 are views illustrating further modifications of my invention.

The electrical circuit of a system embodying my invention is illustrated in Fig. 4. The apparatus comprises an electric discharge tube 61 (preferably a grid-control gas discharge or glow tube), the principal electrodes 69 and II of which are connected to the terminals 'of the coil 31 of a load device 39, and the power for the operation of which is supplied from an alternating current source 13.

The control electrode 15 of the tube 51 is connected through a brush it, to the shaft 11 that supports a conducting disc I9 provided with an insulated sector iii and rotated through a system of gears 83 from a synchronous motor 85. The power for the motor 85 is supplied from the proper current is not passed the same source 13 as supplies the potential between the anode 69 and the cathode 1| of the tube 51.

The disc 19 is engaged by a plurality of fixed brushes 01 that are connected to the terminals 89 and 90 of a power supply source 9| such as a battery. The remaining terminal 92 of the source 9| is connected to the anode 59 of the tube 61.

As the disc 19 rotates, a voltage of predetermined magnitude and of predetermined polarity is impressed on the grid of the tube 51, and as a result the condition of the electric discharge in the tube 01 is varied. In apparatus of the type illustrated in Fig. 7, the grid 15 of the tube 61 is alternately adjusted to negative and positive potentials relative to the anode 59, and the tube is alternately in an unexcited and an excited state, respectively. The load device 39 in turn responds to the condition of the tube 61 and causes the screen to be reciprocated accordinsly.

As illustrated in Fig. 4, the electric discharge tube 51 is of the hot cathode type. It is understood that plural electrode tubes of the coldcathode type are also useable in reciprocating systems of the type described herein. However, where a comparatively heavy current is utilized, it is preferable that the tubes be of the hot cathode type and for the heaviest duty gridcontrolled mercury pool cathode tubes are preferable.

The cathode 1| of the tube requires considerable time to be heated to a proper temperature for emitting, and it is seriously impaired if it emits before it reaches this temperature. A time delay relay 93 is therefore provided for preventing the application of the requisite potential between the anode 59 and the cathode 1| of the tube 51 until the cathode has attained a proper temperature.

Furthermore, it is understood that the potentials applied to the grid 15 by the contact disc 19 must be properly related in polarity to the potentials applied between the principal electrodes 59 and 1| of the tube 61 for satisfactory operation of the system. It is to be noted that by the tube -61 if the grid 15 is of negative polarity relative to the anode 69 at the beginning of each cycle of operation of the disc 19.

The coil 94 of relay 95, equipped with a contactor 98 that is adapted to regulate the activity of the motor circuit, is therefore included in the principal circuit of the tube 61. The contactor 96 is in parallel with the contactor 91 of the time delay relay 93 and when the latter closes the motor circuit is open unless the tube 51 is passing sufficient current. That is to say, power is not supplied to the motor 85 unless the disc 19 is properly oriented in phase relative to the alternations of voltage impressed between the principal electrodes of the tube 51.

Initially the motor 85 is started through the contactor 91 of the relay 93 which is in engagement with the lower fixed contacts of the relay when power is applied. When the cathode 1| is properly excited and the relay 93 is energized, the motor 85 can only be energized through the contactor 96 of the relay 95. If the disc 19 is so oriented at any time that the device 61 remains deenergized for an appreciable interval, the relay 95 is deenergized. When the supply of energy to the motor is thus stopped, its speed decreases and, in coasting, the disc necessarily passes through a condition in which the device 81 becomes energized and the relay 95 receives an impulse to energize it. It is evident that at the time that the relay 95 receives the energizing impulse the rotor of the motor 05 may be moving so slowly that it is pulled into proper step by the engagement of the contactor 98 with its corresponding fixed contacts regardless of how sluggish the relay 95 is. However, in the preferred practice of my invention the relay 95 is a rather quick acting relay.

It is well to point out that the relays 99 and 95 havenot been shown in the modified systems illustrated in Figs. 6, 8 and 9. However,'they have not been incorporated in the views for purposes of clarity. Their incorporation in the actual systems of the type shown in Figs. 4, 6, 8 and 9 will be apparent to one skilled in the art and the relay systems are, as a matter of fact, generally incorporated 'in actual apparatus of this type.

Finally, it is apparent that if tubes of the cold electrode type are utilizedthe time delay relay 99 is not necessary. The circuit is then slightly modified.

It is to be noted that as illustrated in Fig. 4, the restoring force for the movable member II in load device 39 is provided by a tension spring 90. This feature of the illustration should only be regarded as symbolical.

In Fig. 5, the action of the Fig. 4 is illustrated areas 99 under the curve I01 of comparatively small amplitude, represent the periods during which current is flowing through the tube 61. The curve I03, of large amplitude, indicates the position of the movable member 11. The values of positive ordinate, represent its position as it approaches the magnet 39, and the values of negative ordinate represent its position as it retracts from the magnet. The potentials 89 and of the grid are designated below the axis of ordinates on the graph.

As can be seen from the graph, according to my invention, I provide, essentially, a device whereby a mechanical frequency of a predetermined period is attained from an electrical fresystem shown in a frequency of 60 cycles, which is ordinarily available, yields a mechanical frequency of 20 cycles.

It is, furthermore, to be noted that by synchronizing the rotation of the sectored disc 19 with the alternations of the power supplied to the tube 51, I am able to obtain a condition wherein the oscillations of the member l1 are uniform in period and magnitude.

Apparatus of the type illustrated in Fig. 4 may be utilized to attain a mechanical mode of vibration comparatively simple in character. Modes of vibration of more complicated character may be attained with apparatus of the type illustrated in Fig. 6.

The apparatus illustrated in this view comprises a plurality of tubes I05 and I01, herein shown as hot-cathode'grid-glow tubes, the anodes I 09 and I ll of which are connected to two terminals 3 and Ill of a power-transmission transformer H5 and the cathodes H1 and N9 of which are connected to a shaft III whereon a commutator I23, of a predetermined character, is mounted.

The grid I25 and I01 are connected to I21 of the tubes I05 and brushes I29 and HI that graphically. The shaded .the cathodes H1 and II! of the is in such a direction as 82,814 r are adapted to make contact with the segments source, the utility of the improvement, describedv It: and III of the rotating commutator In above is clearly seen. 7 through power sources In and m of suitable n 15 to be noted that the discharge energy is electricalcharacter. The exciting coil 81 of the dissipated in a resistor in the present embodielectro-magnet l! is connected between the electrical center Ill of the secondary I of the transformer Ilt, whereby power is supplied to the tubes III and I01, and the common electrical center I" of the secondary I41 of the transformer Ill. whereby power is supptlilebtgor heating As is illustrated in the view, is impressed on the grid I" or the grid I21 of a tube III! or a tube I01, when the brush II! or the brush I3I associated therewith makes contact with the conducting element I of the come mutator disc I, and correspondingly, the grid is insulated when the brush makes contact with the insulating segment III of the commutator. In the latter case, the corresponding tube breaks down and a current passes through the exciting coil of the magnet.

It is seen that the condition produced in the electro-magnet is determined by the angle between the brushes I29 and Ill and-by the angles subtended by the insulating and the conducting segments I33 and I35 of the commutator disc III.

It has long been known that the passage of a current through an inductor causes a magnetic flux to be set up in the region associated therewith. When the current is decreased the flux decreases in turn, causing the current to maintain itself.

In the present connection, the persisting current tends to produce an electromotive force between the principal electrodes of the tubes I and I01 which in turn tends to maintain the tubes in a state of excitation. Consequently, the character of the mechanical vibrations that the system yields is distorted. I

I have found that this undesirable condition may be eliminated by the addition of a rectifier IBI shunting the coil 31 of the load device 3! and of such polarity that the persisting current from the coil is dissipated in its circuit, and does not pass through the tubes III! and I01. It'is to be noted that when the current through the coil 31 decreases, the voltage across the rectifier to cause it to pass current.

In Fig. 7 the curve I53, wholly above the axis of abscissae, illustrates the condition that is attained in the tubes when the shunting rectifier I5I is not present in the circuit, and the lower curve I54 illustrates the condition when the rectifier I5I is added to the circuit. If the discharge rectifier I5I is included in the circuit, the excess energy represented by the shaded area in Fig. is dissipated therein. The ordinates of the curves may be regarded as proportional to the voltages impressed between the principal electrodes of the tubes in each case.

a negative bias ment of my invention.

It is well to point 'out that in practice the energy may be fed back into the supply'and rendered useful.

As with the apparatus of the type illustrated in Fig. 4, so also in the apparatus described hereinabove, the commutator disc Ifl'is synchronized with the alternations of the power supply source. The disc is-drivenfrom a synchronous motor I! actuated from the same source as the tubes.

Under ordinary circumstances a commutator disc of the well-known type, having conducting and non-conducting segments, may be utilized.

I However, I have found that under certain condi- It will be noted that unless the current in the coil 31 and hence in the last tube is zero before the voltage of the anode III! or I I I relative to the cathode H1 or II! becomes positive, an increase in current in one tube, and therefore in the shaker-coil, results. The consequent motion of the shaker is therefore rather irregular. When it is remembered that the current in the coil 31 and consequently in the last tube to carry the current is under ordinary circumstances. built up during several half-cycles I55 of the power supply source and is required to break down during one half-cycle I58 of the power tions, it is advantageous to employ a disc I51 of the type shown in Figs. 2 and 3.

The disc II] illustrated in these views comprises a plurality of metallic segments I59 and III separated by insulating strips I". One segment I is connected conductively to the drive-shaft of the disc while the remaining segments Itl are insulated therefrom.

when the disc I5! is utilized in apparatus of the type illustrated in Fig. 6, at certain periods during the rotation of the disc, the brushes associated with the tubes are insulated, and as a result the tube corresponding to an insulated brush breaks down and produces a state of excitation in the electromagnet.

It is to be noted that the angle subtended by the segments of the commutator disc may be varied by connecting certain of the segments together with wires I65 bolted in the surface of the segments. The character of the movement produced in the mechanical vibrator may thus be varied.

In Figs. 8 and 9, modifications of my invention are illustrated.

In apparatus of the type illustrated in Fig. 8, the, rectifier Iii provided for dissipating the energy arising from the back-current through the coil of the electrc-magnet I61 is inductively coupled to the coil through which the tube current passes. The tubes I69 and "I are illustrated as cold-cathode grid-blow tubes but the illustration should be regarded only as symbolical. The core I12 is analogous to the core 35 to which reference is made above.

In apparatus of the type illustrated in Fig. 9, independent coils I13 and I15 are provided to correspond to the individual tubes I11 and I19. These coils are magnetically coupled with each other and with the rectifier I5I that is provided for dissipating the energy arising from the backcurrent. The core I corresponds to the core of the apparatus illustrated in Fig. 4.

It is well to point out that, although my inv'ention has been illustrated as specificallyapplied to a mechanical vibrator, certain phases of it have more general applicability. In particular, it is well to reiterate that apparatus of the type illustrated in Fig. 4 or 6 may be utilized teattain a periodic electrical or mechanical disturbance of predetermined properties from a source of power having a series of given properties.

Again, it is to be noted that my invention should not be restricted to apparatus of a type wherein only grid-glow tubes are utilized. Electric discharge tubes of any type, such as thermionic valves or mercury discharge tubes, preferably with keep-alives, may be utilized in certain connections with success. It is, however, of interest to claims.

. point out that for the present application the hotcathode grid-glow tubeof the type designated in Fig. 6 has been found most useful.

I Specifically, it is to be noted that the specific orientation of power sources such as 93 and I31 and I39 should only be given symbolical significance. In apparatus of the type illustrated in Fig. 6, for example, the system can be operated with success if a power supply source is connected between the shaft |2l of thecommutator disc in and the electrical center of the cathodes I I1 and ll! of the tubes I and I0].

I have also found that satisfactory results may be attained with a tube the characteristics of which are such that it may be regulated by alternwy connecting the grid to the anode and the cathode, or by alternately connecting the grid to one principal electrode and allowing it to float freely.

Although I have shown and described certain specific embodiments of my inventiomI am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended I claim as my invention:

1. Control apparatus comprising energy translating means, at least one electric discharge device incorporating a control electrode and a plurality of principal electrodes for transmitting power to said translating means, alternating.

power supply means for impressing an electro-, motive force between the principal electrodes of said electric discharge device, means operating in synchronismwith said power supply means for alternately applying a distribution of potential between said control electrode and said principal electrodes to maintain said electric discharge device deenergized and another distribution of potential between said control electrodes and said principal electrodes to energize said electric discharge device, and means responsive to the current transmitted by said electric discharge device to maintain said potential-distribution-varying means in synchronism with said power supply means.

2. A power system comprising a source of alternating current, a load device, means including an electric valve provided with a control element connected to control only the flow of current from said source to said load device; and means for applying to said control element a periodic bias voltage and a voltage of greater amplitude and period than said bias voltage for permitting current to flow through said load device at times and for preventing current from flowing through said load device at other times.

3. An electrical converting system for tra'nsforming an electromotive force of given characteristics of frequency and amplitude into an electromotive force of predetermined diflerent characteristics of frequency and amplitude, comprising a plurality oi electric-discharge devices, each of said discharge device including a plurality of principal electrodes, and a control electrode, the potentials of said principal electrodes being applied from'said given electromotive force, a rotating commutator device, a source of control power associated with said commutator device, the potentials of the control electrodes being applied through said commutator device from said source of control power and means for controlling the phase relation of the respect to the phaseroi. the potentials applied between said principal electrodes.

the circuit 4. In an electric power system in combination, a load circuit, circuit means connecting the load circuit to a source of alternating current, a vapor-electric conducting meansinterposed in meansi'or controlling and conducting theflow of current to said load circuit at a maximum in half cycle periods, and control means in the vapor-electric means for rendering said vapor-electric means conducting for half cycle or less intervals, said control means including means for interrupting the conductivity of said vapor-electric means after it has been conductive during a predetermined number of hali cycles.

5. In an electric power system, in combination, a source of alternating current, cult, alternating current to the load circuit, electronic means connected in series circuit relation with said circuit means, and control means connected to the electronic means for rendering the electronic means conducting at a maximum in half cycle periods during predetermined intervals and for maintaining said electronic means non conductive during intermediate intervals.

6. In an electric power system, in combination,

. a source of alternating current, a load circuit,

potentials applied to said control electrodes with circuit means connecting the source of alternating current to the load circuit, electronic means connected in series circuit relation with said circuit means for conducting current at a maximum in half cycle periods, and control means connected to the electronic means and operable in synchronism with the source of alternating current for rendering the electronic means conducting for predetermined intervals.

7. In an electric power system, in combination, a source of alternating current, a load circuit, circuit means connecting the source of alternating current to the loadcircuit, electronic means connected in series circuit relation with said circuit means for conducting current at a maximum in half cycle periods, control means for rendering the electronic means conducting for a predetermined number of half cycles of the alternating current, and means for initiating the functioning of the control means.

8. Apparatus for supplying power to a load that requires pulses of current each of which is precisely of a predetermined magnitude comprising a source of alternating current, circuit means connecting said source to said load, electric discharge means interposed in said circuit means for controlling the flow of current-through said circuit, and means for energizing said discharge means, maintaining said. discharge means energized for an interval of time such that a pulse of current of said predetermined magnitude is supplied to said load andv thereafter deenergizing said discharge means.

9-. Apparatus for supplying power to a load that requires pulses of current each of which is precisely of a predetermined magnitude comprising a source of current, circuit means connecting saidsource to said load, means in said circuit means for conducting the flow of current through said circuit, said conducting means being normally non-conducting, and means for actuating said conducting means to conduct current, said conducting means including means whereby it is maintained in conductive condition for an interval of time such that a pulse of current of said predetermined magnitude is delivered to said load and is thereafter rendered non-conductive.

of the collapse of magnetic flux in said inductor,

' during said currentiess intervals in maintain- 10. A power system comprising a load device, a source of periodically pulsating potential, means including an electric valve having a gaseous atmosphere of substantial pressure provided with a control element for supplying current to said load device from said source, and means for applying to said control ele-' mnt a periodic bias voltage of the same frequency as the source and a voltage opposite in eflect to said bias voltage whose period is a multiple of the period of said bias voltage for controlling the conductivity of said valve.

11. In control apparatus of the type incorporating an inductor, alternating power supply means including a full wave electric discharge device having an energized and a deenergized condition, coupled to said inductor and to said power supply'means, means for controlling the energization of said device so that it transmits unidirectional current impulses at least a period 0! the source in length through said inductor, the wave form of said impulses being substantially alike, means for suppressing the influence mg said electric discharge device energized, said last-named means including an asymmetric network and means for coupling said network to said inductor in such manner that it is nonconductive to said unidirectional impulses transmitted through said inductor but is conductive to current impulses having the polarity of the potential generated by the collapse of said flux.

12. An electric timing 'device comprising a circuit adapted to have a current flow therein, a source oi. alternating current, means for initiating the flow of current in said circuit at any predetermined point on the voltage wave of said alternating current, and means for terminating said flow at a predetermined interval after said initiation.

13. In an electric timing device adapted to emit a series of current impulses, a synchronous motor, and .means for regulating the length of each of said impulses according to the angular rotation of said motor.

JOHN W. DAWSON. 

